This invention relates to a front derailleur for a bicycle, and more particularly to improvements in a front derailleur comprising a fixing member fixed to the bicycle frame, two linkage members pivoted to the fixing member, and a movable member having a chain guide and supported to the linkage members, the derailleur being operated by a control wire to move the movable member with respect to the fixing member.
Generally, the control wire for operating the movable member at the front derailleur is accompanied by an outer sheath and is guided therewith. No wire guide is used for guiding the wire because the wire need not extend straight between the front derailleur and a control lever therefor.
In this instance, the outer sheath is required and is curved in a large radius between the lever and the derailleur to thereby reduce resistance against movement of the control wire when guided. As a result, the problem is raised in that the largely curved outer sheath can interfere with a cyclist.
In order to solve the above problem, a control wire having no outer sheath has been proposed, which extends along the bicycle frame. The wire, however, should extend straight along the bicycle frame requiring the provision of a wire guide at a joint of the bicycle frame, for example at the bottom bracket, because the wire is to be bent thereat.
When the sheathless control wire of the so-called bare-type, is used, the wire guide, which is separate from the derailleur, is fixed to the bicycle frame, resulting in an increase in the number of parts and labor for assembly.
Furthermore, a small thickness band is used for fixing the wire guide to the frame to reduce the cost of manufacture and weight. As a result, the band has a smaller tightening strength which allows the wire guide to move as the wire is controlled, thereby raising the problem of changes in wire length.
In order to overcome the aforesaid problems, this invention has been designed. An object of the invention is the provision of a front derailleur capable of guiding the control wire, even of the bare-typed, without using a separate wire guide.
This invention is characterized in that the fixing member at the front derailleur is utilized for mounting a wire guide integrally with the fixing member in such a manner that an extension is provided at the fixing member, the extension extending therefrom downwardly of the bicycle frame until the lowermost end of the extension is positioned in the vicinity of the bottom bracket at the bicycle, and having at the lower end portion the wire guide for guiding the control wire.
Hence, the wire guide can be set in position at the bicycle frame simultaneously when the fixing member of the front derailleur is fixed thereto, thereby enabling the guidance of control wire toward the control lever. As a result, the trouble of mounting a wire guide separate from the fixing member to the bicycle frame is eliminated.
These and other objects and novel features of the invention will be more apparent from the following description in accordance with the accompanying drawings.